JP4687871B2 - Axial gap type electric motor - Google Patents

Description

  The present invention relates to an axial gap type electric motor in which a rotor and a stator are arranged to face each other along the axial direction of a rotor output shaft, and more specifically, an axial gap that can securely fix a rotor magnet to a rotor back yoke. Type motor.

  An axial gap type electric motor is an electric motor in which a rotor (rotor) is disposed oppositely with a predetermined gap on one or both side surfaces of a stator (stator) as shown in Patent Document 1, for example, Compared to a radial gap type electric motor such as a rotor type, the thickness in the direction of the rotation axis can be reduced, that is, it can be made flat.

  Usually, the rotor is composed of a rotor back yoke made of a disc body and a rotor magnet integrally attached to a surface of the rotor back yoke facing the stator. The rotor magnet is integrated with the rotor back yoke by an adhesive or the like. Attached.

  Further, the brushless motor including the axial gap type electric motor is provided with a rotational position detecting means for detecting the rotational position (rotational phase). As an example, in Patent Document 2, a position detection magnet is provided on the outer peripheral surface of the rotor, and a position detection sensor is provided around the rotor.

  Further, Patent Document 2 discloses another technique for performing position detection (sensing) by attaching a position detection sensor to the back side of the rotor back yoke. As another method, Patent Document 3 proposes a method in which a position detection sensor is arranged inside a stator coil.

  However, the conventional axial gap type motor has the following problems. In other words, the axial gap type electric motor has the rotor attracted to the stator side by the magnetic attraction force of the coil during operation. Therefore, there is a possibility that the axial gap type motor may be peeled off only by fixing the rotor magnet as described in Patent Document 1. The rate of occurrence of this peeling phenomenon increases as the motor torque increases.

  In addition, the method described in Patent Document 2 requires a magnet and a mounting member dedicated to position detection, which not only increases the manufacturing cost, but also increases the weight of the rotor itself as the number of detection magnets increases. It cannot be denied that power consumption increases.

  In addition, when a position detection sensor is attached to the back side of the rotor, a communication hole for obtaining a magnetic gap is provided in a part of the rotor back yoke. However, the communication hole is likely to vary in position in the drilling process. Not only that, the distance between the magnet and the position detection sensor becomes longer, so that highly accurate sensing is difficult.

  Furthermore, when a position detection sensor is attached to the stator as shown in Patent Document 3, there is a problem that the position detection sensor is easily affected by a magnetic field generated by the stator and accurate position detection cannot be performed.

JP-A-3-212141 JP 63-92250 A Japanese Patent Laid-Open No. 62-189960

  Therefore, the present invention has been made to solve the above-described problems, and an object of the present invention is to provide an axial gap type electric motor that can prevent the magnet from falling off and can perform more reliable position detection at low cost. There is.

To achieve the above object, the invention according to 請 Motomeko 1, axial to the teeth surface and the magnet surface of the rotor of the stator are opposed to each other with a predetermined gap in the axial direction of the output shaft of the rotor in gap electronic motor, the rotor consists of a rotor back yoke that is coaxially disposed, moldable magnet material attached to the back yokes so as to face the teeth surface of the stator relative to the stator The rotor magnet is composed of a plurality of magnet members divided for each magnetic pole, and each of the magnet members is arranged in an annular shape around the rotation axis. Has two or more through holes for each magnetic pole, and each magnet member has Anchor magnet is arranged on the rear side of the rotor back yoke via the through hole is characterized in that it is integrally formed.

According to a second aspect of the present invention, in the first aspect, the anchor magnet is formed as one pattern so as to cover the through holes .

The invention according to claim 3, Oite to the claim 1, the stator comprises a plurality of core members divided into each teeth, each core member is disposed annularly about said rotation axis It is characterized by having.

The invention according to claim 4, Oite to the claim 1, the rotor magnet is characterized by being magnetized in the thrust direction.

The invention according to claim 5, Oite to the claim 1, the thickness of the rotor magnet is thin at both ends of the rotation direction for each magnetic pole, the center is thicker than the circumferential ends It is characterized by.

According to the first aspect of the present invention, by providing the anchor magnet integrally formed with the rotor magnet on the back side of the rotor magnet, it is possible to prevent the rotor magnet from falling off easily and reliably. In addition, since the rotor magnet is divided for each magnetic pole, the rotor magnet can be effectively prevented from cracking due to the difference in the coefficient of linear expansion between the rotor back yoke and the rotor magnet. Moreover, rotation of each magnet member can be prevented by providing two or more through-holes for each magnetic pole.

According to the second aspect of the present invention, since the anchor magnet is formed as one pattern so as to cover each through hole, not only the rotor magnet can be more reliably prevented from falling off, but also high-precision sensing is performed. be able to.

According to the third aspect of the present invention, since the stator core is formed by arranging a plurality of core members in an annular shape around the rotation axis, the assembling operation is simplified and can be manufactured at a lower cost.

According to the fourth aspect of the present invention, since the magnet is magnetized in the direction perpendicular to the back yoke surface, the orientation of the magnet can be determined with almost no magnetic influence on the rotor back yoke surface. As a result, the magnet can be surely magnetized.

According to the invention described in claim 5 , by increasing the thickness at the center, the magnetic flux density waveform generated by the rotor magnet can be made closer to a sine wave, and noise and vibration during operation can be reduced. .

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an exploded perspective view of an axial gap type electric motor according to a first embodiment of the present invention, and FIG. 2 is a central longitudinal sectional view of the first embodiment. FIG. 3 is a side view of the stator, and FIGS. 4A to 4C are a front view, a rear view, and a cross-sectional view taken along line AA of the rotor according to the first embodiment.

  The axial gap type electric motor 1 includes a stator 2 formed in a disk shape, and a pair of rotors 3 and 3 that are disposed opposite to each other with a predetermined gap (gap) on both side surfaces of the stator 2. The rotors 3 and 3 are coaxially fixed to a rotor output shaft 4 that outputs a rotational driving force.

  The stator 2 and the rotor 3 are accommodated in a cylindrical housing 10. In this example, as shown in FIG. 2, disc-shaped lid members 10a and 10b are provided at both ends of the housing 10, and each motor mechanism is stored therein.

  As shown in FIG. 3, the stator 2 includes a plurality (9 in this example) of pole members 21 a to 21 i arranged in an annular shape with the rotation axis as a central axis. Since each pole member 21a-21i is the same structure, in this example, it demonstrates taking the pole member 21a as an example.

  The pole member 21a is formed by winding a coil 24 (see FIG. 2) around a bobbin having a pair of left and right flange-shaped tooth surfaces 22 and 22, and the bobbin is formed of an electromagnetic steel plate formed in an H shape in a radial direction. It is formed by laminating along.

  Each of the pole members 21a to 21i is entirely covered with an insulator (not shown) made of an insulating resin, leaving the tooth surfaces 22 and 22. The insulator is provided with connecting means (not shown) for connecting the pole members 21a to 21i to each other, and the pole members 21a to 21i are connected in a ring shape through the fixing means.

  The pole members 21a to 21i are connected to each other in an annular manner around the axis by the connecting means, and then integrally fixed with resin by insert molding, whereby the stator 2 is assembled. In this example, the synthetic resin that fixes the outer periphery of the stator 2 also serves as the housing 10.

  Referring to FIG. 2 again, a bearing portion 23 is disposed in the center portion of the stator 2. In this example, the bearing portion 23 has a pair of radial ball bearings 231 and 232, the inner ring is press-fitted into the rotor output shaft 4, and the outer ring side is embedded with a synthetic resin material. In the present invention, the configuration of the bearing portion 23 may be arbitrary.

  In this example, each rotor 3, 3 shares the same rotor output shaft 4, but may be a two-output shaft type in which each rotor 3, 3 has a rotor output shaft. Furthermore, it is good also as a shaft-less type | mold which does not have the rotor output shaft 4, but supports the rotors 3 and 3 directly with respect to the stator 2 via a radial ball bearing.

  Next, the rotors 3 and 3 will be described. Since the rotors 3 and 3 have the same configuration, in this example, description will be given by taking one rotor 3 as an example. In this example, the surface on the side facing the teeth surface 22 of the stator 2 is the front surface of the rotor 3.

  As shown in FIG. 4A, the rotor 3 includes a rotor back yoke 31 that is a disc body disposed coaxially with the stator 2, and a rotor magnet 32 that is integrally attached to the rotor back yoke 31.

  In this example, the rotor magnet 32 is divided into 8 segments by a moldable magnet material (for example, Sm—Fe—Ne based bonded magnet). The rotor magnet 32 is preferably magnetized in the thrust direction, but may be polar anisotropic magnetized.

  The rotor back yoke 31 is made of, for example, a magnetic material such as an electrogalvanized steel plate, and a shaft fixing hole 33 that is press-fitted and fixed to the rotor output shaft 4 is provided at the center. The rotor back yoke 31 is further provided with a plurality of punching holes 34 in an annular shape around the shaft fixing hole 33 for reducing the weight of the rotor back yoke 31 and improving the vibration isolation characteristics.

  In this example, the number of punching holes 34 is eight and each is formed in a fan shape. However, other shapes may be used, and the size and number of the punching holes 34 can be arbitrarily changed according to specifications.

  The rotor back yoke 31 is provided with a through hole 35 for fixing the rotor magnet 32 integrally. The through-hole 35 is a hole that penetrates the rotor back yoke 31 in the axial direction (paper surface direction in FIG. 4A), and is formed in an annular shape around the axis of the rotor output shaft 4. In this example, a total of 16 through holes 35 are provided for each segment of the rotor magnet 32 in pairs to prevent the rotation of each segment.

  By the way, the shaft fixing hole 33 and the punching hole 34 can also be used as guide holes in a mold of an insert molding machine when the rotor magnet 32 is insert-molded. That is, first, the center position is fixed using the central shaft fixing hole 33, and then each punching hole 34 is fitted into a guide rib provided in the mold, thereby positioning in the circumferential direction and positioning reliably. It can be performed. Further, if the through hole 35 is arranged in accordance with the gate position of the mold, the penetration of the resin into the mold becomes smooth, and the molding operation is easier to perform.

  As described above, the rotor magnet 32 is composed of the 8-segment magnet members 32a to 32h. Since each of the magnet members 32a to 32h has the same configuration, only one magnet member 32a will be described as an example.

  The magnet member 32 a is formed in a substantially fan shape having a magnet surface parallel on the front side along the tooth surface 22 of the stator 2. The magnet member 32a is formed integrally with the rotor back yoke 31 by so-called insert molding in which the rotor back yoke 31 is placed in a predetermined mold and resin is poured.

  As shown in FIG. 4B, an anchor magnet 36 that is integral with the magnet member 32 a and the through hole 35 is formed on the back side of the rotor back yoke 31. The anchor magnet 36 is formed in an oval shape as one pattern so as to cover the through holes 35. A total of eight anchor magnets 36 are formed for each segment of the magnet members 32a to 32h.

  The anchor magnet 36 has a role of preventing the magnet member 32a from falling off during operation and a role of a detection magnet as a detected portion of a position detection sensor 51 mounted on the circuit board 5 described later.

  In this example, the anchor magnet 36 is formed as one pattern so as to cover the two through holes 35. For example, as shown in FIG. 5A, one anchor magnet is provided for one through hole 35a. 36a may be formed. This also reliably prevents the magnet member 32a from falling off. In this case, in order to prevent the rotation of each segment, it is preferable that the shape of the through hole 35 is an ellipse or a polygon.

  Further, in this example, the through holes 35a and 35 are provided along the circumferential direction. However, as shown in FIG. 5B, the through holes 35b and 35b are formed along the radial direction. Then, the anchor magnet 36b may be provided there. Furthermore, the anchor magnet 36b may be formed so as to close the space between the through holes 35b and 35b as shown in FIG.

  In this example, the through holes 35b and 35b are provided at two locations along the circumferential direction (FIGS. 4 and 5A) or the radial direction (FIG. 5B), but even more may be provided. Good. That is, as shown in FIG. 5C, the rotor back yoke 31 is provided with three through holes 35c to 35e for one segment, and the anchor magnet 36c is provided for each of the through holes 35c to 35e. Is formed.

  In this example, each through-hole 35c-35e is arrange | positioned so that the vertex of an equilateral triangle may be tied, and it is arrange | positioned circularly for every segment. In this example, the anchor magnet 36c is formed for each of the through holes 35c to 35e. However, as shown in FIG. 5D, the anchor magnet 36d is formed with one through hole 35c being independent, and the remaining magnets One pattern of the anchor magnet 36e covering the through holes 35d and 35e may be formed. According to this, not only can the anchor magnet 36e be fixed more firmly, but also when the outer peripheral side anchor magnet 36e is used for position detection, the component accuracy Since the influence (ratio) of the detection error can be reduced with respect to variations caused by the above, stable position detection can be performed.

  As shown in FIGS. 5A and 5C, when the anchor magnets 36a and 36c to 36e are provided independently, the even-numbered or odd-numbered anchor magnets 36a and 36c to 36e are designated. Then, the position detection sensor 51 may detect it.

  That is, adjacent anchor magnets with the same polarity detect the same polarity. Since there are no magnets between them, the position of each pole can be detected. However, when a strong magnet is used, it may be determined that the magnets have different polarities.

  Referring to FIGS. 1 and 2 again, a circuit board 5 for controlling the operation of the axial gap type electric motor 1 is arranged on the side opposite to the stator of one rotor 3 (left side in FIG. 2). The circuit board 5 is formed of a disc body inserted along the inner diameter of the housing 10, and various electronic components (not shown) are mounted on the mounting surface.

  As shown in FIG. 2, a position detection sensor 51 for detecting the rotational position of the rotor 3 is mounted on the surface of the circuit board 5 that faces the rotor 3. The position detection sensor 51 includes a sensor that detects a magnetic change, such as a Hall sensor, and is relatively disposed on the rotation locus of the anchor magnet 36 of the rotor 3.

  According to this, not only can the rotation of the rotor 3 be easily detected, but also the rotation position of the rotor 3 can be detected directly from the anchor magnet 36 attached to the rotor 3, and a more accurate position can be detected. Detection can be performed.

Next, an axial gap type electric motor according to a second embodiment (reference embodiment) of the present invention will be described. In addition, the same referential mark is attached | subjected to the location considered the same as 1st Embodiment, or the same, The description is abbreviate | omitted.

  In the second embodiment, since the stator of the axial gap type motor 1a is the same as that of the first embodiment described above, only the rotor is illustrated. FIG. 6 is a cross-sectional view of an axial gap type electric motor according to a second embodiment of the present invention, and FIGS. 7A to 7C are a front view, a rear view, and a cross-sectional view taken along line BB of the rotor of the second embodiment. FIG.

  As shown in FIG. 7A, the rotor magnet 32 of the second embodiment is integrally formed in a donut shape on one surface of the rotor back yoke 31 (the front side in FIG. 7A). In addition, you may form for every segment like 1st Embodiment.

  The rotor 3 according to the second embodiment has a rotor back yoke 31 formed in a disk shape and a rotor magnet 32 attached integrally to the rotor magnet 31, and a part of the rotor magnet 32 is a part of the rotor back yoke 31. It is fixed so as to be exposed to the outer peripheral side.

  Also in this second embodiment, as shown in FIG. 7B, the rotor back yoke 31 is provided with a shaft fixing hole 33 at the center, and a plurality of punching holes 34 are arranged annularly on the outer periphery thereof. In addition, a plurality of through holes 35 are annularly arranged at predetermined intervals on the outer periphery thereof.

  The rotor back yoke 31 is further formed with eight notch grooves 37 at 45 ° intervals on the outer peripheral edge thereof. As shown in FIG. 7C, the notch groove 37 is a concave groove formed from the outer peripheral edge of the rotor back yoke 31 toward the center.

  In this example, a part of the rotor magnet 32 is an anchor magnet formed from the side surface side to the back surface side of the rotor back yoke 31 through the notch 37 of the rotor back yoke 31 (front side in FIG. 7B). 36 and a second anchor magnet 38 formed through the through hole 35.

  In accordance with this, the position detection sensor 51 of the circuit board 5 is disposed on the outer peripheral side of the rotor 3, that is, on the outer peripheral side facing the anchor magnet 36 as shown in FIG. 6. According to this, position detection can be performed while preventing the rotor magnet 32 from moving in the radial direction and the circumferential direction via the notch 37.

  In the second embodiment, the position detection sensor 51 is provided on the outer peripheral side of the rotor 3. However, as shown in FIG. 8, for example, as shown in FIG. You may provide in the position facing a stator side.

  As another method, a position detection sensor may be provided in the second anchor magnet 38. According to this, a plurality of circuit patterns on the circuit board can be prepared, and the detection position can be arbitrarily set according to the specifications of the motor. Can be changed.

  In the above-described embodiment, the rotor magnet 32 has the rotor magnet 32 and the anchor magnet 36 connected via the through hole 35 (or the notch groove 37), as shown in FIG. In addition to this, as shown in FIG. 9B, the anchor magnet 36 may be embedded on the rotor back yoke 31 side, and according to this, the rotor 3 as a whole is formed. It can be formed thinner.

  As a still more preferable aspect, the thickness of the rotor magnet 32 is set to the outside in the circumferential direction for the purpose of reducing the noise and vibration during operation closer to the magnetic flux density waveform generated by the rotor magnet. It is desirable to reduce the thickness and form the center thicker.

  That is, as shown in FIG. 9C, tapered surfaces may be formed on both ends of the rotor magnet 32 to increase the thickness on the center side. Alternatively, as shown in FIG. Thus, the tapered surface may be formed in an arc shape.

  As another embodiment, as shown in FIG. 9E, a recess may be formed in the rotor back yoke 31, and the rotor magnet 32 may be embedded in the recess. At this time, by forming tapered surfaces at both ends of the concave portion, both ends can be made thin and the central portion can be made thick.

  In the embodiment described above, the auxiliary magnet member 36 is formed in a round shape or an oval shape. However, as in the present invention, a part of the rotor magnet 32 is formed on the back side (or side surface side) using the through hole 35. If exposed, its shape, size, number, etc. can be arbitrarily changed according to the specifications.

  Further, in the above-described embodiment, an axial gap type electric motor having a configuration in which the tooth surface of the stator having high efficiency such as reduction of cogging torque is 9 slots and the number of rotor poles is 8 poles is used. However, the present invention can be applied to an electric motor having a basic axial gap structure.

1 is an exploded perspective view of an axial gap type electric motor according to a first embodiment of the present invention. The longitudinal cross-sectional view of the axial gap type electric motor of the said 1st Embodiment. The front view of the stator of the axial gap type electric motor of the said 1st Embodiment. The front view, rear view, and AA sectional view of the rotor of the said 1st Embodiment. The front view which shows the modification of a rotor. The longitudinal cross-sectional view of the axial gap type electric motor which concerns on 2nd Embodiment (reference embodiment) of this invention. The front view, rear view, and AA sectional view of the rotor of the said 2nd Embodiment. The longitudinal cross-sectional view which shows the modification of the said 2nd Embodiment. Explanatory drawing explaining the modification of the rotor magnet 32. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1a Axial gap type electric motor 2 Stator 3 Rotor 31 Rotor back yoke 32 Rotor magnet 32a-32h Magnet member 33 Shaft fixing hole 34 Punching hole 35 Through hole 36 Anchor magnet 37 Notch groove 4 Rotor output shaft 5 Circuit board 51 Position detection sensor

Claims (5)

In the axial gap type electric motor in which the teeth surface of the stator and the magnet surface of the rotor are arranged to face each other with a predetermined gap along the axial direction of the output shaft of the rotor,
The rotor is perforated and back yokes arranged coaxially at, and a rotor magnet comprising a moldable magnet material attached to the back yokes so as to face the teeth surface of the stator relative to the stator And
The rotor magnet is composed of a plurality of magnet members divided for each magnetic pole, and each of the magnet members is annularly arranged around the rotation axis,
The rotor back yoke is provided with two or more through holes for each magnetic pole,
An axial gap type electric motor in which each magnet member is integrally formed with an anchor magnet disposed on the back side of the rotor back yoke through the through hole . The axial gap type electric motor according to claim 1 , wherein the anchor magnet is formed as one pattern so as to cover each through hole . 2. The axial gap type electric motor according to claim 1, wherein the stator includes a plurality of core members divided for each tooth, and the core members are annularly arranged around the rotation axis. . 2. The axial gap type electric motor according to claim 1, wherein the rotor magnet is magnetized in a thrust direction. 2. The axial gap type electric motor according to claim 1, wherein the rotor magnet has a thickness that is thin at both ends in the rotation direction and thicker at the center than at both ends in the circumferential direction for each magnetic pole.

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